From mboxrd@z Thu Jan  1 00:00:00 1970
From: Imre Deak <imre.deak@intel.com>
Subject: Re: [Intel-gfx] [PATCH v2] PM / Runtime: Introduce
 pm_runtime_get_noidle
Date: Thu, 10 Dec 2015 11:43:50 +0200
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To: "Rafael J. Wysocki" <rjw@rjwysocki.net>, Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Intel graphics driver community testing & development <intel-gfx@lists.freedesktop.org>, linux-pm@vger.kernel.org

On Thu, 2015-12-10 at 01:58 +0100, Rafael J. Wysocki wrote:
> On Wednesday, December 09, 2015 06:22:19 PM Joonas Lahtinen wrote:
> > Introduce pm_runtime_get_noidle to for situations where it is not
> > desireable to touch an idling device. One use scenario is periodic
> > hangchecks performed by the drm/i915 driver which can be omitted
> > on a device in a runtime idle state.
> >=20
> > v2:
> > - Fix inconsistent return value when !CONFIG_PM.
> > - Update documentation for bool return value
> >=20
> > Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> > Cc: linux-pm@vger.kernel.org
>=20
> Well, I don't quite see how this can be used in a non-racy way
> without doing an additional pm_runtime_resume() or something like
> that in the same code path.

We don't want to resume, that would be the whole point. We'd like to
ensure that we hold a reference _and_ the device is already active. So
AFAICS we'd need to check=C2=A0runtime_status =3D=3D RPM_ACTIVE in addi=
tion
after taking the reference.

--Imre